A conventional computer system that handles large-scale data manages the data by using a large-capacity storage apparatus provided separately from a host system.
When an existing storage apparatus is to be replaced with a new storage apparatus in such a computer system, it is necessary to migrate data stored in the existing storage apparatus to the new storage apparatus in order to continue using the data stored in the existing storage apparatus. In order to do so, the computer system is required to be capable of migrating the data without stopping data transmission or reception between a host computer and the storage apparatuses. Furthermore, when migrating the data between the existing storage apparatus and the new storage apparatus, a method that does not require any special function in already installed apparatuses/devices such as the existing storage apparatus, the host computer, and a network is favorable.
In this case, for example, Patent Literature 1 mentioned below discloses a technique for migrating data by setting logical units in an existing storage apparatus as external volumes, then migrating an access target of a host computer to a new storage apparatus by using an alternate path program and then copying data stored in the logical units belonging to the existing stored apparatus to logical units belonging to the new storage apparatus by using a copy function. If the data migration method disclosed in Patent Literature 1 is used, it is possible to migrate data between the storage apparatuses without using any special function of the existing storage apparatus or the network or without stopping data transmission or reception between the host computer and the storage apparatuses.